Expression Of Myelin Markers Research Articles

The Evolving Use of Gold Nanoparticles as a Possible Reversal Agent for the Symptoms of Neurodegenerative Diseases: A Narrative Review.

Neurodegenerative diseases are broadly hallmarked by impaired energy metabolism and toxic intracellular accumulations such as damaged organelles or reactive oxygen species (ROS). Gold nanoparticles readily cross the blood-brain barrier and increase nicotinamide adenine dinucleotide + hydrogen (NADH) oxidation to nicotinamide adenine dinucleotide (NAD+), which is vital for intracellular energy generation, cellular repair, and protection from ROS. Thus, the use of gold nanoparticles to treat and potentially reverse cellular injury seen in neurodegenerative disease has been an area of ongoing research. This systematic review explores current literature regarding the use of gold nanoparticle therapy in the treatment of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). In vitro studies of CNM-Au8 (Clene Nanomedicine, Salt Lake City, UT) have been shown to reduce TDP-43 aggregates associated with ALS. These studies also exhibited the neuroprotective effects of CNM-Au8 in rat primary neurons exposed to amyloid-beta peptides, which are associated with Alzheimer's disease. In animal models of MS, oral delivery of CNM-Au8 was demonstrated to produce robust and significant remyelination activity, oligodendrocyte maturation, and expression of myelin markers. In these same MS animal models, CNM-Au8 improved the motor function of cuprizone-treated mice in both open-field and kinematic gait studies. Recent phase II trials of CNM-Au8 in 13 patients with Parkinson's disease and 11 patients with stable relapsing MS demonstrated a statistically significant increase in the NAD+/NADH ratio across two cohorts. As the current data repeatedly suggest, these gold nanoparticles are efficacious for the treatment and reversal of symptoms across these varying neurodegenerative pathologies. Further opportunities exist for increasing human trials and eventually incorporating this new technology into existing treatment regimens.

Acer truncatum Bunge seed oil ameliorated oxaliplatin-induced demyelination by improving mitochondrial dysfunction via the Pink1/Parkin mitophagy pathway.

Dietary nutritional support for special populations is an effective and feasible method to improve the quality of life of patients and reduce medical pressure. Acer truncatum Bunge seed oil (ATSO) is widely recognized for its ability to promote nerve myelin regeneration. To evaluate the ameliorative effects of ATSO on chemotherapy-induced demyelination, a zebrafish model of chemotherapy-induced demyelination was established. The results showed that 100 μg mL-1 of ATSO reversed tail morphology damage, axon degeneration, touch response delay, ROS level upregulation and the expression of myelin basic protein decrease in chemotherapy-induced zebrafish. In addition, the expression of myelin markers (including sox10, krox20, and pmp22) in oxaliplatin-induced cells was markedly reversed by ATSO and its active components (gondoic acid, erucic acid, and nervonic acid). ATSO and its active components could reverse demyelination by ameliorating mitochondrial dysfunction. Conversely, linoleic acid and linolenic acid promoted demyelination by exacerbating mitochondrial dysfunction. Moreover, the Pink1/Parkin pathway was recognized as the main reason for ATSO and its active components improving mitochondrial function by activating mitophagy and restoring autophagic flow. Taken together, this study demonstrated that ATSO and its active components could be further developed as novel functional food ingredients to antagonize demyelination.

Analgesic Effect of Perineural Injection of BoNT/A on Neuropathic Pain Induced by Chronic Constriction Injury of Sciatic Nerve in Rats.

This study was designed to investigate the analgesic effect of perineural injection of BoNT/A on neuropathic pain induced by sciatic nerve chronic constriction injury (CCI) and possible mechanisms. SD rats were randomly divided into Sham group, CCI group and BoNT/A group. Paw mechanical withdrawal threshold (pMWT) and paw thermal withdrawal latency (pTWL) of each group were detected at different time points after surgery. The expression of myelin markers, autophagy markers and NLRP3 inflammasome-related molecules in injured sciatic nerves were examined at 12days after surgery. Moreover, C-fiber evoked potential in spinal dorsal horn was recorded. The expression of SNAP-25, neuroinflammation and synaptic plasticity in spinal dorsal horn of each group were examined. Then rats treated with BoNT/A were randomly divided into DMSO group and Wnt agonist group to further explore the regulatory effect of BoNT/A on Wnt pathway. We found that pMWT and pTWL of ipsilateral paw were significantly decreased in CCI group compared with Sham group, which could be improved by perineural injection of BoNT/A at days 7, 9 and 12 after surgery. The peripheral analgesic mechanisms of perineural injection of BoNT/A might be related to the protective effect on myelin sheath by inhibiting NLRP3 inflammasome and promoting autophagy flow, while the central analgesic mechanisms might be associated with inhibition of neuroinflammation and synaptic plasticity in spinal dorsal horn due to inhibiting SNAP-25 and Wnt pathway. As a new route of administration, perineural injection of BoNT/A can relieve CCI induced neuropathic pain probablyvia both peripheral andcentral analgesic mechanisms.

Effect of modulating glutamate signaling on myelinating oligodendrocytes and their development-A study in the zebrafish model.

Myelination is crucial for the development and maintenance of axonal integrity, especially fast axonal action potential conduction. There is increasing evidence that glutamate signaling and release through neuronal activity modulates the myelination process. In this study, we examine the effect of manipulating glutamate signaling on myelination of oligodendrocyte (OL) lineage cells and their development in zebrafish (zf). We use the "intensity-based glutamate-sensing fluorescent reporter" (iGluSnFR) in the zf model (both sexes) to address the hypothesis that glutamate is implicated in regulation of myelinating OLs. Our results show that glial iGluSnFR expression significantly reduces OL lineage cell number and the expression of myelin markers in larvae (zfl) and adult brains. The specific glutamate receptor agonist, L-AP4, rescues this iGluSnFR effect by significantly increasing the expression of the myelin-related genes, plp1b and mbpa, and enhances myelination in L-AP4-injected zfl compared to controls. Furthermore, we demonstrate that degrading glutamate using Glutamat-Pyruvate Transaminase (GPT) or the blockade of glutamate reuptake by L-trans-pyrrolidine-2,4-dicarboxylate (PDC) significantly decreases myelin-related genes and drastically declines myelination in brain ventricle-injected zfl. Moreover, we found that myelin-specific ClaudinK (CldnK) and 36K protein expression is significantly decreased in iGluSnFR-expressing zfl and adult brains compared to controls. Taken together, this study confirms that glutamate signaling is directly required for the preservation of myelinating OLs and for the myelination process itself. These findings further suggest that glutamate signaling may provide novel targets to therapeutically boost remyelination in several demyelinating diseases of the CNS.

PACAP and VIP increase the expression of myelin- markers in rat schwannoma cells

Defining the mechanisms regulating peripheral myelinogenesis in vitro remains a daunting task. One of the major complications is related to the inability of Schwann cells to produce myelin in vitro. However, a limited number of schwannoma cell lines are now being accepted as adequate model systems to study myelin expression since they present most of the features that characterize normal myelinating Schwann cells. PACAP and VIP peptides have been shown to play part in myelin maturation and synthesis in the central nervous system, but no data regarding their potential actions have been reported in the peripheral nervous system, particularly in vitro. In this study, we investigated the effects of both peptides on the expression of myelin-specific markers using the well-established rat RT4 schwannoma cell line. In addition, we endeavored to partly unravel the underlying molecular mechanisms involved. Expression of myelin-specific markers (MAG, MBP and MPZ, respectively) was assessed in cells grown either in the presence of normal serum (10% FBS) or serum starved and treated with or without 100nM PACAP or VIP. Effects of pharmacological blockade of PACAP and VIP receptors as well as of the main signaling pathways on the expression of myelin-markers were also determined. Our data shows that serum starvation (24h) was sufficient to induce a significant increase in the expression of myelin markers. This result was paralleled by a concurrent increase in the endogenous expression of both peptides, as well as of the non-specific PACAP/VIP receptor 2 (VPAC2), but not of VPAC1 or PAC1. Exogenous PACAP or VIP treatment further exacerbated starvation-driven expression of myelin markers, suggesting an active role of these peptides in myelin generation. Interestingly, stimulation with either peptides increased phosphorylation levels of Akt at Ser473 residue whereas they did not affect Erk1/2 activation. Treatment with the PAC1 receptor antagonist (PACAP6-38) had no effects on myelin markers expression while a non-specific VPAC receptor antagonist completely abrogated both starvation and/or starvation + peptide-induced expression of myelin markers. Similar effects were obtained in cell pretreated with the PKA inhibitor (H-89, 10μM), suggesting that peptide-driven induction of myelin markers occurs preferentially via the canonical PKA/Akt signaling pathway. In conclusion, the results here presented provide the basis for future studies on the role of these peptides in physiological myelination and in demyelinating pathologies such as Charcot-Mary-Tooth disease.

Selective effect of hypothyroidism on expression of myelin markers during development.

Thyroid hormones are critical for maturation of the central nervous system. In a previous study, we showed a change in the pattern of mature myelinated nerve fibers by 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in developing hypothyroid animals, which suggests a possible role for thyroid hormones in myelin compaction. The classical myelin markers myelin basic protein (MBP) and proteolipidic protein (PLP) are expressed later in oligodendroglial development, when myelin sheath formation is in progress. A myelin constituent designated myelin-associated/oligodendrocytic basic protein (MOBP) has been identified and related to myelin compaction. We assessed the developmental sequence of appearance of CNPase, MBP, MOPB, and PLP proteins in cerebellum (Cb) and corpus callosum (cc) in an experimental hypothyroidism model. The appearance of both MOBP isoforms occurred at postnatal day (P)25 and P30 in cc and Cb, respectively, followed by an increase with age in the control group. However, all the MOBP isoforms were weakly detectable in both regions at P30 from the hypothyroid (H) group, and the higher molecular weight isoform remains decreased in cc, even at P90. The developmental pattern of expression of CNPase, MBP, and PLP proteins was also delayed in the H group. CNPase and MBP expression was recovered in cc and Cb, whereas PLP remained below control levels at P90 in cc. Our data show that the experimental hypothyroidism affects the developmental pattern of the oligodendrocytic/myelin markers. Furthermore, thyroid hormone may modulate specific genes, as demonstrated by permanent down-regulation of MOBP and PLP expression in adulthood.

Immunohistochemical characterization of axonal sprouting and reactive tissue changes after long-term implantation of a polyimide sieve electrode to the transected adult rat sciatic nerve

The development of artificial microstructures suited for interfacing of peripheral nerves is not only relevant for basic neurophysiological research but also for future prosthetic approaches. Aim of the present study was to provide a detailed analysis of axonal sprouting and reactive tissue changes after implantation of a flexible sieve electrode to the proximal stump of the adult rat sciatic nerve. We report here that massive neurite growth after implantation, steadily increasing over a period of 11 months, was observed. Parallel to this increase was the expression of myelin markers like Po, whereas non-myelin-forming Schwann cells did not change. Compared to five weeks post-implantation, where both Schwann-cell phenotypes were intermingled with each other, non-myelin-forming Schwann cells occupied a peripheral position in each microfascicle after 11 months. After an initial increase, hematogenous macrophages were down-regulated in number but maintained close contact with the implant. However, at no time were signs of its degradation observed. It is concluded that the introduced flexible polyimide electrode is suitable for contacting peripheral nerves since it permits substantial neurite growth and offers excellent long-term stability.

Thyroid hormone affects Schwann cell and oligodendrocyte gene expression at the glial transition zone of the VIIIth nerve prior to cochlea function.

All cranial nerves, as well as the VIIIth nerve which invades the cochlea, have a proximal end in which myelin is formed by Schwann cells and a distal end which is surrounded by oligodendrocytes. The question which arises in this context is whether peripheral and central parts of these nerves myelinate simultaneously or subsequently and whether the myelination of either of the parts occurs simultaneously at the onset of the cochlea function and under the control of neuronal activity. In the present paper, we examined the relative time course of the myelinogenesis of the distal part of the VIIIth nerve by analyzing the expression of peripheral protein P0, proteolipid protein and myelin basic protein. To our surprise, we observed that the expression of myelin markers in the peripheral and central part of the intradural part of the VIIIth nerve started simultaneously, from postnatal day 2 onwards, long before the onset of cochlea function. The expression rapidly achieved saturation levels on the approach to postnatal day 12, the day on which the cochlea function commenced. Because of its importance for the neuronal and morphological maturation of the cochlea during this time, an additional role of thyroid hormone in cochlear myelinogenesis was considered. Indeed, it transpires that this hormone ensures the rapid accomplishment of glial gene expression, not only in the central but also in the peripheral part of the cochlea. Furthermore, an analysis of the thyroid hormone receptors, TRaplha and TRbeta, indicates that TRbeta is necessary for myelinogenesis of the VIIIth nerve. Rapid thyroid hormone-dependent saturation of myelin marker gene expression in Schwann cells and oligodendrocytes of the VIIIth nerve may guarantee nerve conduction and synchronized impulse transmission at the onset of hearing. The thyroid hormone-dependent commencement of nerve conduction is discussed in connection with the patterning refinement of central auditory pathways and the acquisition of deafness.